This invention relates to a device for eliminating gas or paraffin hydrate deposits that form inside drilling equipment or hydrocarbon production or transportation equipment. The device as set forth in the invention can be applied in the oil industry, in particular in the extraction at sea of liquid or gaseous hydrocarbons at great depths, and in the transportation of these hydrocarbons.
A device for eliminating the paraffin or bitumen deposits that form on the inside wall of piping, for example in tubular equipment located in the center of an oil production well or in an oil transportation pipe-line, is described in the Russian patent RU 2 109 127. This device, mounted inside the piping, contains a heat generator, mechanical means for cleaning the piping wall and means for moving along the piping. The heat generator consists of a reacting liquid with an exothermic decomposition reaction. This liquid is stored in a reservoir that is connected, via a valve, to a reactor and to a decomposition chamber. The decomposition chamber is equipped with ducts through which jets of gaseous products from the decomposition of the reacting liquid are ejected while the heat generator is operating. These jets heat the paraffin or bitumen deposits that are present on the inside wall of the piping.
However, this device has the disadvantage of only being able to operate by stopping the circulation of hydrocarbons inside the piping. Furthermore, it must be moved using a drive means, for example using a cable, which considerably limits the field of application.
Through U.S. Pat. No. 4,456,069, we know of a device intended to increase the temperature and the pressure inside a well bore in order to increase the permeability of the formation located at the bottom of the well. This device is located at the head of the well and consists of a gas generator in which a reactant is decomposed by a catalyst to form very hot decomposition gases and of an air compressor to inject compressed air into the well. But, such a device is not suited to the elimination of gas and paraffin hydrate slugs that settle on the wall of the hydrocarbon transportation pipes that can be several kilometers in length and be submerged at great depths on the sea floor.
The object of this invention is to remedy these disadvantages and therefore to propose a device for the elimination of gas or paraffin hydrate deposits that form on the inside wall of hydrocarbon production or transportation pipes, through the use of a reactant that is likely to decompose when high temperatures are produced and where said device is characterized by the fact that it consists of:
an annular decomposition chamber mounted in a sealed manner around a section of said piping, where said chamber consists of a catalyst that promotes the decomposition of said reactant,
a reservoir for the reactant that feeds said decomposition chamber with said reactant so as to heat the hydrate and paraffin deposits using the heat that emanates from the decomposition of the reactant by the catalyst,
an output tube (11) for the evacuation of the products that result from the decomposition of the reactant outside the decomposition chamber,
and means of injection (13, 14) of a flushing fluid under pressure inside the decomposition chamber in order to carry said products that result from the decomposition toward the output tube.
The reactant is chosen from the group consisting of hydrogen peroxide, hydrazine and ethylene oxide.
The catalyst can be a solid catalyst chosen from the group consisting of a metal oxide, iron, platinum and silver. This catalyst can be deposited on a ceramic support. The catalyst can also be a liquid catalyst chosen from the group that contains iron nitrate and iron sulfate.
According to another characteristic, the device of the invention also consists of means for injecting a liquid additive into the decomposition chamber in order to facilitate the initiation of the decomposition reaction of the reactant.
According to another characteristic of the invention, the inside wall of the reactant""s decomposition chamber is lined with a material that resists high temperatures.